1. Field of the Art
This invention relates to a polymer composition containing modified metal powder. More particularly, it relates to an improvement in anti-oxidizing stability of a metal powder-blended polymer.
A metal powder-blended polymer is provided with the properties peculiar to the metal such as electroconductive or magnetic properties and thus can be applied to a variety of uses utilizing these properties.
2. Prior Art
Conventional metal powder-blended polymer compositions, especially polymer compositions blended with iron or iron alloy powder, are readily oxidized and often rust when practically used because a metal powder is generally more chemically active than metal articles. Such rusting lowers the electroconductive and magnetic properties of a metal, and even a small degree of rusting sometimes lowers the commercial values of products because of poor appearances.
To deal with such problems, methods for improving the anti-oxidizing stability have been proposed. Examples of such methods are a method of covering the surfaces of metal powder with an organic rust-resisting agent (e.g., Publn. Nos. of Unexamined Pat. Applications 63494/76, 8798/78 and 77270/79), a method of using alloy powder (Japanese Laid-Open Patent Application No. 7153/71 Specification), a method of oxidizing and covering the surfaces with dense metal oxide layers (e.g., Publn. No. of Unexamined Patent Application 147502/83), and a method of chromate treatment.
Even by the use of the metal powder treated according to these rust-preventing methods, however, long-term anti-oxidizing stabilities required for such metal powder-containing compositions have not been fully satisfactory, and further improvement has been demanded.